The present disclosure generally relates to hot melt adhesive dispensing systems, and more particularly to an adhesive cut-off module for hot melt adhesive dispensing systems.
Hot melt adhesives and hot melt adhesive dispensing systems are well known. A bull head, which is an adhesive bead formed at the start of an adhesive stream, and an angel hair formed at the end of a run have been known concerns for using hot melt adhesive applicators. Bull heads can result in wasted adhesive and in some instances can cause discomfort if the adhesive bead ends up in a location where it is in contact with an end user. The formation of adhesive beads or bull heads is believed to be caused by air friction slowing a leading edge of an adhesive stream.
Angel hairs are formed due to a poor adhesive cut-off at a nozzle, which creates a thin strand of adhesive. Angel hairs can foul machine components and also cause adhesive to end up in locations that can cause discomfort for an end user. Angel hairs, which are fine adhesive fibers, can be caused by an adhesive shut-off, which is set back some distance from an orifice. When an adhesive module is shut off, adhesive flow is stopped. However, due to its high viscosity, the hot melt adhesive begins to stretch into small filaments, sometimes continuously, without breaking for a long period of time. It is this extra volume from the module shut-off to the orifice exit in conjunction with the high viscosity of the hot melt adhesive that result in undesired angel hairs.
Accordingly, there is a need for improved hot melt adhesive dispensing systems including an improved adhesive cut-off module.